How to Grow Aster Flowers

Aster flowers are perennials with star-shaped flower heads, often mistaken for daisies. When other flowers begin to fade in late summer and early fall, that's when aster flowers will bloom and bring beautiful color to your garden. Today we'll show you how to grow aster flowers in your garden, care for them, and harvest them.

Aster flowers are perfect for wall garden, wildflower gardens, or next to a hedge. They grow from about 8-9 inches tall and will look amazing in any garden. The great thing about asters is that they will bloom in late summer or even early autumn, when most flowers have already finished their cycle. 

Planting Aster Flowers

• Aster flowers like cooler summers, especially cooler nights.
• Prepare to plant your asters in early to mid spring and fertilize the soil prior to planting.
• Plant them in a spot with partial to full sun. If you live in a tropical or subtropical area, plant asters in the shade to avoid the hot summer mid-day sun.
• Plant your aster flowers in well drained, moist, and humus rich soil.
• You can certainly grow aster flowers from seeds, but it is rather tricky as they don't always germinate. You can start the seeds indoors in the winter and keep them in the refrigerator for 4-6 weeks. After 4-6 weeks, move the seeds to a sunny spot. Place the seeds about 1 inch deep. To learn more about how to grow asters from seeds, see the video below!
• It's best to plant young asters in mid to late spring. Full grown asters that are already potted can be planted as soon as they become available at your nearest nursery. 
• Space your aster flowers 1-3 feet apart.
• After planting, give your flower lots of water and add mulch to keep the roots cool, retain moisture, and prevent weeds.

How to Grow Asters From Seed:

Caring for Aster Flowers

• Add a thin layer of compost and a 2 inch layer of mulch around your aster flowers every spring. Alternatively, you can also add a portion of balanced fertilizer.
• Make sure they receive about an inch of water per week, especially during warm summers. Keep in mind that asters are water sensitive, meaning that giving them too much water or not enough water, will cause them to lose their flowers and foliage. Keep a close eye on the flowers, and and try different watering methods. 
• If you're growing the tall varieties, you can stake them so they don't topple over.
• In early summer, pinch the asters back once or twice to promote more bloom and bushier growth. 
• Cut your aster flowers back in the winter after the foliage has died. You can also leave them as is during the winter. 
• Divide your flowers every 2-3 years to keep them healthy and vibrant.

Pests and Diseases

Asters are susceptible to a few different types of pests and diseases. Keep a close eye on the flowers to make sure that they're vibrant and healthy. If you have pest problems, try this DIY garden insecticide.

• Powdery mildew
• Leaf spots
• Aphids
• Nematodes
• Tarsonemid mites
• Rusts
• Stem cankers
• Snails and slugs
• White smut

Storage and Harvest

Once asters have bloomed, they make some pretty amazing cut flowers! Simply cut the stem (it can be as short or as long as you want) using a pair of gardening shears or a sharp knife. Then, place the flowers in a vase with fresh water. Keep your flowers fresh for longer by adding a little bit of sugar to the water.

Aster Varieties

Because asters are native to North America, the most common varieties are the New England aster and the New York aster. Both varieties are great for pollinators.

North American Aster Varieties:

• New England asters (S. novae-angliae) – Typically larger than New York asters, New England asters come in a variety of colors from magenta to deep purple.
• New York asters (S. novi-belgii) – There are actually a lot of different New York aster varieties, and their colors range from bright pink to bluish purple. They also may be double, semi double, or single.
• Blue Wood aster (S. cordifolium) – This variety is more bushy than the other two, and and have small blue to white flowers.
• Heath aster (S. ericoides) – The heath aster is similar to creeping phlox as they are a ground cover aster variety, and have small, white flowers.
• Smooth aster (S. laeve) – This variety of aster is tall and upright with small lavender blue flowers.

European Aster Varieties:

• Frikart's aster (Aster x frikartii) – This Swiss variety has large lilac-blue flowers and is mid-sized.
• Rhone aster (A. sedifolius) – These varieties are known for their small, star-shaped flowers that are lilac-blue in color and very compact.

Happy Planting!